There is an apparatus employing the Rankine cycle provided with a transmission mechanism in which a refrigerant pump and an expansion device are provided on an identical shaft and the shaft is coupled to a rotary shaft of an engine via an electromagnetic clutch, whereby rotation of the engine is assisted using power regenerated by the expansion device (see Patent Document 1). An expansion device rotation speed sensor that detects a rotation speed of the expansion device and a current sensor that detects a current flowing through an electromagnetic coil of the electromagnetic clutch are provided additionally in the apparatus. A diagnosis as to whether the electromagnetic clutch is stuck in an engaged condition or not is made on the basis of detection values detected by these sensors.
Patent Document 1: JP2012-193690A